First, I want to say that yes I know sometimes the official way to write this character's name is 'Lecien' but this is so obviously wrong, so I always use Lucien. GCrest sometimes makes ...questionable choices when romanizing their character names. We talk about it on the Discord, we mock it in the wiki staff group, and it'll never get better. It doesn't help that GCrest also sometimes changes their mind and will issue a 'new way' to read the character name in English. The wiki uses one official way of reading his name (Lecien) but I have official merchandise that spells it 'Lucien'. I don't even know which spelling they're going with now; there's just no winning. Since Lucien's name is clearly supposed to originate from Lucifer, plus the Japanese uses a 'Lu-' sound instead of a 'Le-' (ルシアン), his name will always be Lucien on my site.
Honestly that's my only real comment. Lucien is pretty sparing when he speaks, so there wasn't a lot of dialogue I had trouble with. There were a few lines, mostly in the Sun route when he's addressing the diet, where I had to translate them, then mark them and go back because I knew they weren't quite right but I couldn't think of what it needed to be. But that happens on almost every translation, so it's not really noteworthy. I had to try and get a little creative with some of the translations because there are a few too many times where our main character is talking about how much her heart/chest is hurting from how sad Lucien is. But really, there's only so many ways you can say the same thing over and over again! So go ahead and enjoy everyone's favorite emo angel.